Javascript 可迭代的技术定义是什么，您如何对其进行测试?

I've been implementing a useful subclass of the ES6 Set object. For many of my new methods, I want to accept an argument that can be either another Set or an Array, or really anything that I can iterate. I've been calling that an "iterable" in my interface and just use .forEach() on it (which works fine for a Set or an Array. Example code:

// remove items in this set that are in the otherIterable
// returns a count of number of items removed
remove(otherIterable) {
    let cnt = 0;
    otherIterable.forEach(item => {
        if (this.delete(item)) {
            ++cnt;
        }
    });
    return cnt;
}

或者

// add all items from some other iterable to this set
addTo(iterable) {
    iterable.forEach(item => {
        this.add(item);
    });
}

但是，我怀疑我可能并不真正支持 ES6 定义的任何可迭代对象，所以我对 Javascript 可迭代对象的真正定义使用 ES6 规范中的术语感兴趣?

function looksIterable(o) {
    return typeof o[Symbol.iterator] == "function";
}